Ptv780-ah01 TV was left on for 36 overnight and all day. Has sound but no video.

Well, I'm assumig you've already attempted just turning it off and letting it sit for a few hours. I would also recommend unplugging it and letting it sit for a few hours before plugging it back in and turning it back on. These TV's have this problem fairly often, and it's normally a result of a bad flyback transformer, which is a part you need to order from the manufacturer. I would advise having a licensed repairman replace the part, because it is fairly difficult. Even with practice, things can still be broken.
The flyback transformer is the component that generates the large amount of voltage required to drive a CRT. If you decide to replace this component yourself, order service manual #7566 from Philips - it will give you a lot of schematics and tips that are very useful.